Sodium Phosphate, Dibasic → Methyl cis-3-t-butoxycarbonylamino-4-oxoazetidine-2-carboxylate

Beteiligte Stoffe

Reaktionsschritte

A solution of 10.5 g (26.7 mmole) of methyl 3-t-butoxycarbonylamino-1-(2,4-dimethoxybenzyl)-4-oxoazetidine-2-carboxylate in 500 ml of acetonitrile is degassed with argon and warmed to 80°. A degassed solution of 15 g (55.5 mmole) of potassium persulfate and 7.5 g (28 mmole) of sodium monohydrogen phosphate in 150 ml of water is added in five portions over 1 hr. The reaction is stirred at 80°-85° under argon for 2-3 hrs until all starting material is consumed (tlc). The reaction mixture is cooled, concentrated in vacuum, shaken with ethyl acetate-water. The organic phase is washed with dilute HCl, NaHCO3 solution and brine; dried over magnesium sulfate and evaporated to dryness. The residue is chromatographed over silica gel with 1:1 benzene-ethyl acetate to afford pure product which crystallized from ethyl acetate-hexane to yield 2.0 g (31%) of the title compound. A less pure fraction from the column, is crystallized from ethyl acetate-hexane to give an additional 0.5 g of product, overall yield, 38%.

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